Multiple conductor electrode



6- 28, 1969 l. E. BENTOV MULTIPLE CONDUCTOR ELECTRODE Filed March 24,1966 J5EE III/I0" jnuenz orx- Ill United States Patent 3,474,791MULTIPLE CONDUCTOR ELECTRODE Itzhak E. Bentov, Belmont, Mass., assignorto Brunswick Corporation, a corporation of Delaware Filed Mar. 24, 1966,Ser. No. 537,031

Int. Cl. A61n 1/04; H01b 7/04 US. Cl. 128-418 11 Claims ABSTRACT OF THEDISCLOSURE An electrode having high break-resistance and flexibility andparticularly suitable for implantation in a human body for conductingheart stimulating electrical currents from a suitable current supply tothe heart muscle. The electrode structure comprises a plurality offlexible electrical conductors wrapped longitudinally and coaxiallyaround a break-resistant, flexible, electrically conductive core, withthe opposite ends of the conductors electrically connected to the core.The conductors and core are enclosed by an outer coaxial flexibleinsulating sheath arranged to expose the conductors at a pointintermediate their ends.

This invention relates to electrical conductors and in particular to anelectrode for use such as a cardiac pacer.

A number of devices have been developed heretofore for externalelectrical stimulation of a heart which has stopped beating or which isbeating improperly as one which is fibrillating. An early example ofsuch a device is that shown in Hyman et al. Patent No. 1,913,595. Thepresent invention comprehends an improved electrode structure forconducting heart stimulating electrical currents from a suitable currentsupply to the heart muscle in such pacer apparatus.

Thus, a principal feature of the present invention is the provision of anew and improved electrode structure.

Another feature of the invention is the provision of such an electrodestructure comprising an improved heart pacer electrode.

A further feature of the invention is the provision of such an electrodestructure having new and improved construction providing long life atrelatively low cost.

Still another feature of the invention is the provision of such anelectrode structure providing improved circuit redundancy for improvedmaintained conductive functioning of the electrode.

A yet further feature of the invention is the provision of such anelectrode structure having new and improved means for facilitatingconnection thereof to the heart muscle by the implanting surgeon.

Another feature of the invention is the provision of such an electrodestructure having new and improved means for preventing deteriorationthereof by body fluids and the like.

Another feature of the invention is the provision of such an electrodestructure having a new and improved axial core construction providingimproved functioning thereof.

A further feature of the invention is the provision of such an electrodestructure wherein the core construction is formed of a plurality ofextremely fine metal filaments.

Other features and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingwherein:

FIGURE 1 is a fragmentary elevation of an electrode structure embodyingthe invention electrically connected between a suitable electricalcurrent supply and a heart muscle;

FIGURE 2 is a fragmentary enlarged view of a portion of the electrodeimplanted in the heart muscle;

FIGURE 3 is a broken diametric section of the electrode prior to theinstallation of the stitching needle to one end thereof;

FIGURE 4 is a fragmentary, enlarged isometric view of a mid-portion ofthe electrode;

FIGURE 5 is a transverse section taken substantially along the line 55of FIGURE 3;

FIGURE 6 is a fragmentary side elevation of the stitching needleattached to the end of the electrode with portions thereof shown indiametric section; and with a severing means shown fragmentarily forremoving the stitching needle from the electrode upon completion of theimplantation of the electrode in the heart muscle; and

FIGURE 7 is a schematic electrical wiring diagram of the circuitarrangement of the electrode.

In the exemplary embodiment of the invention as disclosed in thedrawing, an electrode generally designated 10 is shown to comprise anelongated flexible structure having one end 11 connected by a suitableconnector 12 to an electrical power supply 13 for providing suitableelectrical current through the electrode 10 to a heart muscle, such asmuscle 14. As shown in FIGURE 1, the opposite end 15 of the electrode issecured to the heart muscle 14 as by stitching 16. In the illustratedembodiment, a pair of electrodes 10 is provided for conducting theelectrical current both to the heart muscle and back to the power supply13; each of the electrodes is substantially identical and thus thefollowing specific description thereof will be limited to a singleelectrode.

Referring now more specifically to FIGURES 2 through 5, the electrode 10includes an axial elongated core 17 formed of a flexible, breakresistantmaterial. In the illustrated embodiment, core 17 comprises a 300 endyarn formed of an electrically conductive material, such as 304stainless steel filaments each having a cross-section of approximately12 microns with the filaments having approximately 5 to 7 turns per inchtwist therein. The filaments are impregnated with an elastomer, such assilicone rubber, which may be suitably cured as by heating in an oven atapproximately 400 F. The core may be of suitable length, and in theillustrated embodiment, is approximately 28 inches long.

A silicone rubber sheath 18 is then provided over the core. As shown inFIGURE 3, a first end 19 of the sheath is spaced from one end 20 of thecore to provide an exposed outer end 21 of the core, and the oppositeend 22 of the sheath 18 is spaced from the opposite end 23 of the core.The end 23 may be twisted back upon itself to define an enlarged endsuitable for connection thereto of a stitching needle, such as needle 24shown in FIGURE 6. The silicone rubber sheath 18 may be provided on theyarn in any suitable conventional manner such as by extrusion thereonto,or by providing the sheath in a form of a tube which may be suitablycemented to the core after being drawn thereover. The sheath preferablyis fixedly retained against axial slippage on the core.

A plurality of electrically conductive cables are wound helically aboutthe sheath, herein a pair of cables 25 and 26 are provided degreesapart. Cable 25 has a first end 27 secured in electrical contact withthe core 17, and cable 26 has a first end 28 secured in electricalcontact with the core adjacent first cable end 27. Cable 25 has a secondend 29 secured in electrical contact with the core end 23, and cable 26has a second end 30 secured in electrical contact with the core end 23adjacent cable end 29. Herein, cables 25 and 26 are formed of platinumand comprise seven strand cables wherein each strand has a diameter ofapproximately .001 inch.

The electrode further includes an outer sheath 31 having an outer end 32coplanar with end 19 of sheath 18 and an inner end 32' spaced inwardlyof the inner end 22 of the sheath 18 with the connections 29 and 30 ofthe platinum cables being disposed within the outer sheath 31 inwardlyof the inner sheath end 22 and with the end 23 of the core extendingoutwardly therefrom. As best seen in FIGURES 2 and 3, the outer sheath31 is provided with a gap 33 at a point outwardly of the inner sheathend 22. In the illustrated embodiment, the gap 33 may be approximatelyfour inches outwardly of sheath ing to the right from gap 33 and portion31b extending to the left therefrom. The sheath portions may be suitablyprovided as by extrusion thereof onto the subassembly of the core 17,sheath 18, and conductors and 26,

or by drawing of preformed tubular sheath structures onto thesubassembly for positive retention thereon as by cementing. As shown inFIGURES 1 through 3, means are provided for indicating the location ofthe gap 33, herein in the form of a pair of black marks 34 and adjacentgap 33 on sheath 18 to be viewable through portions 31a and 31brespectively of sheath 31.

As indicated above, the electrode 10 may be provided with a stitchingneedle 24 secured to the end 23 of core 17 thereof for use by thesurgeon in implanting the electrode suitably in the heart muscle .14. Asbest seen in FIGURE 6, the needle may comprise an arcuate needle havingan attaching end 36 provided with an axial outwardly opening recess 37.An electrically conductive ferrule 38 is secured to the end 23 of theelectrode core as by soldering and the core end 23 with the ferrule 38secured thereto is retained in the recess 37 as by crimping of theneedle end 36 illustratively shown at 39.

The electrode 10 may be utilized as follows. The surgeon may firstlyinstall the power supply 13 under the patients skin in the abdomen orupper left chest cavity with the ends 11 of the electrode suitablysecured to the connectors 12. The electrodes are drawn through the spacebetween the internal organs of the patient and the rib cage to adjacentthe heart. As shown in FIGURE 1, the distal ends of the electrodes arethen stitched into the heart muscle 14 by means of the needle 24 todispose the exposed cables 25 and 26 at gap 33 within the heart musclethereby making electrical contact therewith. As shown in FIGURE 1, theends of the electrodes are brought out from the heart muscle whereby theblack marks 34 and 35 indicate to the surgeon the accurate centering ofthe gap 33 in the heart muscle. The exposed portions of the electrodeadjacent the heart muscle may be suitably stitched thereto by surgicalsutures 16. The needle 24 is removed from the end of the electrode as bycutting the end 15 by suitable means such as scissor blades as shown inFIGURE 6. The cut end of the electrode may be suitably capped if desiredas by insulating cap 41. A loop is retained in the electrodes adjacentthe heart to preclude tugging of the electrodes by the heart movements.In the illustrated embodiment, the heart muscle 14 is the left ventricleportion of the heart with the ends 15 of the electrodes extending towardthe apex 42 thereof.

Illustratively, the power supply 13 may provide a current pulse ofapproximately 14 milliamperes at 6 to 7 volts and of approximately 2millisecond duration. Referring to FIGURE 7, the current pulse isdelivered to the exposed conductors 25 and 26 at gap 33 by threeseparate paths, thereby providing an improved long life characteristicof the electrode as a result of the circuit redundancy. Morespecifically, the current pulse may flow to the exposed portion of thewire 25 at gap 33 from the power supply 13 through the core portion 17to the contact 4 27- and thence through the conductor 25. Similarly,'thecurrent pulse may be delivered to the exposed portion of the conductor26 at gap 33 by delivery of the current from power supply 13 throughcore 17 to the contact 28 and thence through the conductor 26. As theopposite ends of the conductors 25 and 26 are also electricallyconnected to the core 17 at points 29 and 30, a plurality of additionalcurrent flow paths to the exposed portions of the wires 25 and 26 isprovided. More specifically, should a break in the wire 25 occur betweenthe gap 33 and the point 27 the pulse could still be delivered to theportion of the conductor 25 at gap 33 through the core 17 to contact 30and thence back to the exposed portion of the conductor at gap 33, aswell as from the conductor 26 through contact 29 to contact 30. Asimilar supply of the current pulse to the exposed portion of conductor26 at gap 33 would be provided in the event of a break in the conductor26 between gap 33 and contact 28. Still further, should a pair of breaksoccur, one each in conductors 25 and 26 between gap 33 and contactpoints 27 and 28, the current pulse could still nevertheless bedelivered to the exposed portions of the conductors 25 and 26 at gap 33by delivery thereof through the core 17 and thence through contactpoints 29 and 30 tothe exposed portions of the conductors. Stillfurther, by virtue of the improved redundancy circuitry of theelectrode, a break in one of the conductors 25 and 26 between the gap 33and the contact point 29 or 30 thereof, in addition to breaks in each ofthe conductors between the gap 33 and the contacts 27 and 28 would stillpermit current flow to the other of the conductors in gap 33 through thecore 17 and thence through the unbroken portion of the conductorextending backwardly to the gap 33.

Thus, electrode 10 provides an improved low cost, high reliabilityelectrode adapted for use in such critical applications as heart pacerconductors.

While I have shown and described one embodiment of my invention, it isto be understood that it is capable of many modifications. Changes,therefore, in the constructions and arrangement may be made Withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

I claim:

1. An electrode comprising: an elongated core of flexible,break-resistant, electrically conductive material; a plurality offlexible electrical conductors extending longitudinally of and coaxiallyabout said core and electrically connected to said core at opposite endportions of said conductors; and an outer sheath of flexible insulatingmaterial coaxially about said core and electrical conductors andarranged to expose said electrical conductors at a point intermediatesaid opposite end portions of said conductors.

2. The electrode of claim 1 wherein said core is formed of a pluralityof filaments having a diameter of under approximately one-half mil.

3. The electrode of claim 1 wherein said core comprises a yarn of metalfilaments impregnated with an elastomer.

4. The electrode of claim 1 wherein said electrical conductors comprisea plurality of stranded cables.

5. The electrode of claim 1 wherein an intermediate sheath of flexibleinsulating material is disposed coaxially about said core, saidelectrical conductors being wrapped about said intermediate sheath.

6. The electrode of claim 1 wherein said conductors extend helically andare spaced from each other intermediate said end portions thereof.

7. The electrode of claim 1 wherein said electrical conductors comprisea pair of conductive elements extending helically degrees apart.

8. The electrode of claim 1 further including means adjacent said pointat which said electrical conductors are exposed for indicating thelocation of the exposed portion References Cited of said electricalconductors.

9. The electrode of claim 1 further including a con- UNITED STATESPATENTS t 1 t 11 M h H t dt nd 1,687,912 10/1928 Wheeler 174-115 Xiltezrgcrfe ec r1ca y a mec amca y connec e 0 one e 2,581,213 1952 pp174 115 X 10. The electrode of claim 1 wherein said outer sheath 53,035,583 5/1962 Hlrsch et 128418 X is formed of two spaced portionsdefining between them 3,216,424 11/1965 Chadack 128-418 said point atwhich said electrical conductors are exposed. 3367339 2/1968 Sesslons128418 11. The electrode of claim 10 wherein an intermediate sheath offlexible insulating material is disposed coaxially 1O WILLIAM KAMMPnmary Exammer about said core, said electrical conductors being wrappedUS, Cl, X R about said intermediate sheath. 174-114, 115

